1. Technical Field
The present invention relates to a liquid container made of flexible sheet, adapted to internally store a liquid for supply to a liquid consuming apparatus.
The invention relates primarily to a liquid container suitable as an ink pack for internally storing ink that is to be supplied to an ink-jet printer as the liquid consuming apparatus.
2. Description of the Related Art
Ink packs designed to internally store ink to be supplied to an ink-jet printer, and composed of flexible sheets having liquid outlet member (22) for feeding the ink to the ink-jet printer are known in the art (see Patent Citation 1 for example).
This kind of ink pack has a pair of side wall portions disposed facing one another, and a gusseted portion that defines a gusset between the pair of side wall portions.
In an ink pack of this type, the gusseted portion progressively folds in jackknife fashion as the ink inside is consumed; if during this process the fold line jackknifes in such a way as to protrude outward, there will be considerable resistance to folding, resulting in a larger amount of ink that is not ultimately consumed but instead remains left in the ink pack.
Particularly where an ink pack is designed with a gusseted portion situated at the bottom, the fold line of the gusseted portion will tend to protrude outward (downward) due to the weight of the ink.
According to the teachings of Patent Citation 1, a regulating member (17) adapted to regulate the folding face from bending outwardly is provided inside the case which houses the ink pack.
However, the teachings of Patent Citation 1 require provision of the regulating member, which is inherently superfluous in terms of ink delivery. Moreover, it is not a simple matter to accommodate both the regulating member and the ink pack within the case.
Furthermore, because in the initial state the regulating member inwardly indents the gusseted portion, the amount of ink filling the ink pack will be smaller.
Another known conventional ink pack is provided with regulating plates (11) designed to regulate collapse of the pack in a uniform manner as the ink is consumed (Patent Citations 2, FIG. 3).
An ink pouch of so-called gusset type embodying this teaching is depicted in model cross section in FIGS. 9A-D. In the drawing, regulating plates 2 are shown applied to the side faces of a pack (flexible pouch) 1 composed of flexible sheeting.
FIG. 9A depicts a condition in which the pack 1 has been filled with a relatively small amount of ink. In this condition, due to the low weight of the ink inside the pack, the gusseted portion 3 that constitutes the base part will maintain chevron shape with the fold line 3a as the apical line.
Consequently, as the ink inside the pack is consumed, the ink pack 1 will collapse in such a way that the gusseted portion 3 progressively folds inward as depicted in FIG. 9B. This is the preferred condition, as the amount of residual ink left inside the pack 1 will be minimized.
FIG. 9C on the other hand depicts a condition in which the pack 1 has been filled with a relatively large amount of ink. In this condition, due to the heavy weight of the ink inside the pack, in the gusseted portion 3 that constitutes the base part of the pack 1, the bottom will distend downwardly so that the fold line 3a forms a downwardly pendant valley part.
Thus, as the ink inside the pack is consumed, the gusseted portion 3 will fold up with its fold line 3a protruding downward as depicted in FIG. 9D. This is an undesirable condition, as a large amount of residual ink will be left inside the pack 1. Such a condition can easily occur if the ink pack is left at high temperature when first used.
Thus, according to the teachings of Patent Citation 2, if the ink pack is filled with a large amount of ink to the point that the gusseted portion distends outwardly, the problem of a considerable amount of ink being left behind at completion of use of the ink pack will arise.    [Patent Citation 1] Japanese Unexamined Patent Publication 2005-254570    [Patent Citation 1] Japanese Unexamined Patent Publication 2002-361882